For example, in a fluid dynamic bearing device disclosed in Patent Literature 1, a bearing sleeve made of a sintered metal is fixed to an inner periphery of a bottomed cylindrical housing, and a shaft member is inserted along an inner periphery of the bearing sleeve. The shaft member is supported by a dynamic pressure action of a lubricating oil, which is to be generated in radial bearing gaps formed between an outer peripheral surface of the shaft member and an inner peripheral surface of the bearing sleeve. A sealing member is fixed to an end portion of the bearing sleeve, and the lubricating oil filling an inside of the housing is sealed by this sealing member. Specifically, the sealing member comprises an integral piece of a disk-like first sealing portion to abut against an end surface of the bearing sleeve and a cylindrical second sealing portion to abut against an outer peripheral surface of the bearing sleeve. A first seal space is formed between an inner peripheral surface of the first sealing portion and the outer peripheral surface of the shaft member, and a second seal space is formed between an outer peripheral surface of the second sealing portion and an inner peripheral surface of the housing. As described above, when the second seal space is formed on an outer-diameter side with respect to the radial bearing gaps, an axial dimension of the first seal space arranged in axial alignment with the radial bearing gaps can be reduced. Thus, bearing rigidity can be increased by reducing an axial dimension of the bearing device or by increasing a radial bearing span.
The above-mentioned sealing member is formed, for example, by injection molding of a resin.
Further, in the above-mentioned fluid dynamic bearing device, between the sealing member and the bearing sleeve, there are formed communication paths for communicating the first seal space and the second seal space to each other. Those communication paths enable pressure balance of the lubricating oil retained in both the seal spaces to be properly maintained.
Further, a fluid dynamic bearing device disclosed in Patent Literature 2 comprises: a shaft member; a bearing member having an inner periphery along which the shaft member is inserted; and a sealing member provided at an opening portion of the bearing member so as to seal a lubricating oil filling an inside of the bearing member. The sealing member of this fluid dynamic bearing device is formed by injection molding of a resin.